EyeLine Golf Putting Laser+ This laser fires down two lines - a line pointing to your target, and a line along the face of the putter, square to the target line Improve your putting almost instantly! Since the Laser creates lines, it's easy to see if the putter moves off-target. Easily snaps on the front of the putter shaft with a twist of the wrist Create vivid visual images for recall For use indoors only. Each set of batteries lasts up to two hours of continuous use.